Art and apparatus for debarking pulp slabs



June 12. 1928.

R. H. PANGBORN ART AND APPARATUS FOR DEBARKING PULP SLABS gwventop June 12. 1928. 1,673,265

I R. H. PANGBORN ART AND'APPARATUS FOR DEBARKING PULP SLABS Filed Oct. :51, 1927 a Sheets-Sheet 2 4 I 4 gwue'ntoz Red mono! H Eng born Patented June 12, 1928.

UNITED STATES PATENT OFFICE.

REDMOND H. PANGBORN, OF TACOMA, WASHINGTON, ASSIGNOR CFTWO-THIRDS TO F. C. BREWERAND R. H. SHAFFER, BOTH OF TACOMA, WASHINGTON.

ART AND AIPARATUS FOR DEBARKING PULP SLABS.

Application filed October 31, 1927. SerialNo. 229,941.

My invention relates to the art of strip ping the bark from sawmill slabs .in order to render the wood thereof available for use in a pulp milLaud to the apparatus employed therein. r

The objects of my invention are, first, to provide a means of utilizing the waste wood of sawmills, especially in such mills as han dle logs of large diameter in which the bark is often several inches in thickness; second, to provide a machine adapted to be fed slabs of any length, width, or thickness, liavingba'rk of an y thickness, in a continuous manner; third, which acts on the slabs in accordance with the particular characteristics ofeach slab, automatically gouging thereinto to depths sutlicient to remove all the bark thereof in a series of relatively narrow strips or steps; fourth, which is successive in its action on any one slab, the central portion thereof being first cleared of bark, thenthe two nextmntiguous portions, then those "further removed from the center, and soon until the entire bark surface has been removed from the slab.

A further object to provide a means of automatically preventing the cutter from going too deeply int-othe wood of the slab and thereby preventing the undue wastage of wood. Another object to provide a device which is sensitive to the position of the wood under the bark. rather than the surface of the bark. Another object is to pro vide for the adjustment of the mechanism,

whereby the wear of the parts may be read ily taken up. Another object is to provide a pneumatic means or controlling the pressure of the cutting mechanism on the slab. Another object is to provide adjustmentof the bark gaging device, whereby similar tools may be used economically on different parts of the machine, the device being set further out from its center for those parts engaging near the edge of the slab than for those engaging "the central portion thereof. y t 1 attain these and other objects by the devices, mechanisms, andarrangements illustrated in the accompanying drawings, in whichi 1 I Figs. '1 and 2 are'side elevation and plan,

. respectively, my complete machine, Show ing it in use; Fig. 3 is a cross-section there of on the line in Fig. 2; Fig. 4 is an enlarged side elevation of one oi the opernoved therefrom.

showing the cutter head removed; Fig. 6 is a side elevation of the parts shown in Fig. 0; and Fig. 7 is a cross-section, on a larger scale, of a portion of the slab being debarked, showing a part thereof already debarked and showing the position of the next cutter head and its gage spider.

Similar numerals oi. reference refer to similar parts throughout the several views.

It is well known. that the bark of, the tree which is to be used in making wood pulp for paper making, must first be re- The problem of reinoving the bark from the western timber entirely ditifei'ent from that arising from trees grown in the eastern and southern por-- tion of the country and no machine has yet been developed which is able to economically operate with the western conditions. i

My machine is primarily intended for use on western growth of timber and especially to the slabs of outer wood which are cut from the logs in western lumber mills. These slabs'are cut lengthwise of the log and comprise a segment of the log having the bark on the curved side. Since the bark is of varying thickness, and is-rough and often knotty, it is impossible to gagethe distance that the wood surface removed from the bark surface by merely following a certain depth below the surface of the bark. i y

I have solved this problem by guiding the cutter head by means of a spider havalong the table 1. Suitable guiding means,

indicated at 5 (Fig. 2) maybe provided on the table 1, adapted to engage the sides of the slabs 4 whereby each slab is directed to dent with the-center of the machine.

bring its central axis substantially coincifeed chain 3 may have sharp prongsfi to hold the slabs 4 in such position asthey pass through the machine. The slabs 4 may be of any length and thickness, and thin narrow slabs may be followed by thick broad ones, but I have shown them, in the drawings, as being of uniform size, in order to show the consecutive action of the parts of the machine on a single slab.

The table 1 is also provided with uprights 7 arranged periodically along both sides, and these are joined together, over the top 1 of the "table by means o'fhorizontal bridge pieces 8. .Horizontal transverse shafts 9 are mounted in the uprights 7 and extend across a the machine below the said bridges '8. The

any other suitable driving means.

shaft 9 of the first framing, formed by the parts 7 and8, is driven by a belt 10 on a pulley 11, on the outerend of the shaft, or It has a sprocket wheel mounted'on the inner side of the same upright 7.

bearings 16 secured to the under side of the bridges 8 (Figs. land 4). 7

The list shaft 9 is preferably provided with one only of the following described cutter arms, but the others are'each provided with two. However, since they are similar, the description of one will apply to all, with the understanding that those acting on the right or left ofthe central axis are provided with right-hand or left-hand cutter heads. i

As above stated, the slab 41- passes axially through the machine, therefore a cutter head 17, engaging and cutting into the slab and rotating on an axis at right-angles to the direction of motion of the slab, will cutfa strip of the bark therefrom. The cutter heads 17 are therefore arranged in the machine in such position as to out such stripsin consecutive order, the arms supporting the cutter heads 17 from one shaft 9 being displaced laterally from those on the next shaft by a space equal to the widthof the cutter head.

Referring particularly to Figs. 3 and 4 it will be seen that each cutter head 17 is supported on the ou'terfree end of an arm, the upper'end of which is supported onand pivoted about the shaft 9. Two bearings 18 are journaled on the shaft 9 and each is provided with a. tubular "19 screwed thereinto. The two arms 19 arev similar and are provided with rightand left-hand screw threads at the two ends. The outer ends of ings 20. r A shaft21 is mountedin the two bearings 20. The alinement of the shaft 21 and its distance fronrtheshaft 9. is controlled by turning one or the other of the arms-19 in the bearings 18 and 20; i A sprocket Wheel 22 is mounted on the shaft 9 "between the two bearings 18. A-smaller sprocket wheel 23 is mounted on the shaft 21 between the two bearings 20. The sprocket wheels 22 and 23 are of the same pitch and are connected together by a sprocket chain shaft 9. The sprocketwheels 22 and 23 and the-chain 24 are enclosed by a suitable metal box 25. The end of the shaft 21 which lies nearest the central axis of themachine, ex-

tends beyond the bearing 20 and-carries the spider disk 26, loosely mounted thereon, next to the said bearing, and the cutter head17 is tightlymounted on the outer end.

Referring particularly to :Figs. 5 and 6,2

the spider disk 26 rotates freely on the shaft 21 and is provided with a series of. radial grooves 27 on the, side next (to the cutter thevarms 19 are screwed intothe outer bear- 2 1. Therefore the shaft 21 is rotated by the head 17. Each groove 27 is also provided with a radial slot 28. The spider rays 29 lie in the grooves 27 and are secured therein, adjusted position, by=clamping screws 30 which pass through the slots 28. The rays 29 may be of'any desired form, andI have illustrated one suchform inthe draw ings. In this form the ray 29 is chisel shaped, having-its outer endand one side beveled and sharpened as shown;

, The spider rotates entirely independent of the shaft 21, on which itismounted, in

factv it rotates in the opposite direction thereto; It is rotated entirely by contact with the moving slab 4, as it passes.- Each ray 29 cuts into the bark of the advancing slab 4, the sharpened corner first entering the bark'a'nd thencutting down deep thereinto, as the spider rotates, until it engages the relatively hard .wood below the bark.

At this point it is directly under the shaft 21 and is supporting -the said shaft. The weight of thefree endof the arm, and all its parts, together with the reaction of the 2 chain 24,'pressesthe spider rays 29'into the I bark so that its point or endlpasses-completely through the bark and a short dis-. tance into the wood of the slab. If the-bark is thinner in one place than another the spinder reaches down only to the wood and therefore allows the cutter head 17 to cut away only the same quantity of woodfrom' the slab as it would if thebark were thicker.

In each case the spider lowers :the cutter head only so far as will insure its cutting all the bark away from the strip on which it is operating. a

.arm, by a pivot connection 35.

Referring now to Fig. 7 it will be seen that, since the spider rays 29 are on the side of the cutter head 17 further removed from the central axis of the machine and of the slab, the said spider gages the lowest been cutby the cutter heads of the machine which this particular part of the slab has passed before reaching thepoint at which the sectionis taken, and the next cutter head 17 is about to cut the third such step, as shown by the broken lines in said view. It will also be understood from this view, that the adjustment of the rays 29 for those arms which are further removed. from the central axis of the machine must be such that the outer sharpened edge will extend slightly further from the center of the shaft 21, in relation to the cutting-line of the cutter head 17, than those nearer to the center, because of the difference in the angle made by the bark-wood joint to the horizontal. Also it will be seen from this view that the chisel-like form of the rays 29 tend to push the soft bark towards the cutter head.

I have also provided pneumatic means of increasing or decreasing the pressure of the free end of the arm on theslab, as illustrated in Figs. .3 and 1-. This consists of a cylinder 32 mounted to oscillate on trunnions mounted in hangers 33 secured to the under side of the bridge frame 8. This cylinder 32 has a piston 34 which connected to the top of the gear b01125, of the A suitable air pipe 36 leads tothe cylinder 32, through .the triuinions or otherwise, and the air pres sure applied therein is transferred through the piston 34 and the box 25 to the arm.

Therefore an increase of air pressure in the cylinder 32 will mean an increase in downwardpressure of the spider on the slab. Suitable means for controlling the air pressure. may be provided but not shown herein.

Thus it will be seen that I am able to remove all the bark from a slab by pass ing it successively past a series of cutter heads, each positioned in a definite relation to the others and to the central axis of the slab, whereby first the central portion of the bark of each slab is cut away and then the cut away part is widened on each side by each pair of cutter heads untfl the whole has been removed. Also, when the slabs are in short lengths, the machine may be acting on many slabs at the same time.

The above-described method of. removing the bark from slabs seems to be the only practical solution of the problem presented in handling western timber.

Though the above-described machine might be said to be an assembly of independent machines,'yet, as a matter of fact,

they are all cooperating to produce a single result winch none could accomplish alone,

the tying-in feature being the feeding and guiding means whereby the slab is passed in the central position through the successive portions of the single machine.

of the machine, as above described, can, of course, be varied; as, for instance, the drive of the several shafts may be changed; the construction of the arms may be altered; and the drive of the cutter heads may be different, without alfecting, in any substantial way, the machine. so, too, the spider described may have its chiseLshaped rays changed to pointed rays, or it may con'iprise a sawshaped disk, or even a thin circular disk, so long as it is able to penetrate through the soft bark and to reach the hard wood below it, without departing from the spirit of my invention.

Having, therefore, described my invention, what I claim is 1. The art of debarking slabs, comprising moving a slab axially past a series of rotating cutter heads; each cutter head being oli set from the position of the other cutter heads relatively to the slab; guiding the slab in its motion past the cutter heads; pressing the cutter heads into the slab; and limit ing the downward motion of the cutter heads by the height of the wood of the slab under thebark being removed.

2. In a debarking machine, the combination ofmeans for moving a slab axially therein; a rotating cutter head; means supporting mitting free vertical movement thereof in the. machine; and means, mounted on said.

supporting means, and adapted to pass through thebark of the slab to contact with the wood thereui'lder, whereby said cutter head is limited in its. downward movement by the position of the surface of the wood under the bark.

In a debarking machine, the combination of means for moving a slab axially therein; rotating cutter head; means sup porting the rotating cutter head and permitting free vertical movement thereof in the machine; and means, mounted adjacent said cutter head and on said supporting means, and adapted to pass through the bark of the slab to contact with the Wood thereunder at a point adjacent the lowest point of cutting of said cutter head, whereby said cutter head is limited in its downward move ment by. the position of the surface of the wood under the bark.

4. In a debarking machine, the combination of means for moving a slab axially therein; a pivoted arm mounted in the machine Theparticular form of the various parts the rotatin cutter head and per lot) and adapted to swing vertically therein; a

rotating cutter head, mounted on the free end of said arm; and means mounted on said pivoted arm, adjacent to said cutter head, andadapted' to passthrough the bark of the slab to contact with the wood thereunder at a point adjacent the lowest point of cutting otsaid cutter head, whereby said arm andcutter headla-re limited in their downward movement by the posltlon ofthe surface oi the Wood under the bark.

75 In a debarkmg machine, the combina tion o'tmeans for moving a slab axially on said arm, adjacent to said cutter head,

' and adapted to pass through the bark of the slab to contactwith the wood thereunder at apoint adjacent to thelowcst point of cut ting'of said cutter head, whereby said arm and cutter head are limited intheir downward movement by the position of the surface of the wood underv the bark.

6. In debarkl ng machine, the combination of means for moving a slab axially therein; a rotating cutter head, adapted to cut the barltfrom saidslab, and cutting with a motion opposed to the motion of the slab therepast; means supporting said rotating cutter head and permitting 'iree vertical movement thereof in, the machine; and means, mounted on said cutter-head-supporting means, and tree to be rotated thereon in; a direction opposite to that of the cutter head bythc motion of the slab therepast, and

adapted to pass through the bark of the slab .to contact with the wood thereunder, whereby said cutter head is limited in its downward movement by the position of the surface of the Wood under the bark;

,7. In a. debarking machine,the combina- ;tion" of means for moving a slab axially therein; a irame bridging across the mar chine,above the slab; an] arm pivotally mounted in said bridging frame and adapti-.

ed to swing vertically"therein; a rotating cutter head, mounted on the free end otsald arm; means mounted on saidarm and adapt ed to pass through the bark of the slab to contact with the wood thereunder, whereby said arm and cutter head are limited in their downward movement by the position of the surface of thewood under the bark; and pneumatic means interposed between sald bridging irame and said arm, whereby the downward pressure of said arm, with its cutter head and its lilrntmg means, may be controlled.

8. In a deharking machineadapted to strip a. longitudinal section of bark from the curved side of a slab, the combination with mean; tor movmg the slabaxlally therein,

with its curved side exposed; a rotating cutter head; means supporting the rotating cutter head and permitting free vertical DVQHlEEilt thereof in the machine, said cutter head being strip of bark from said slabas it is moved therepast; and limiting means, coaxial with and adj acent said cutter head, said limiting means being positioned on'that side of the cutter head turthest removed from the central axis of the slab, and adaptedto pass through the bark of the slab to contact with the wood thereunder,whereby said cutter head is limited in its downward movement, to cut con'ipletely through the bark and a limited distance into the wood, byjthe posi-e tion of the surface of "the woodunder the bark and immediately adjacentthe strip being cut.

REDMONDY PANGBORN.

adapted to cut a longitudinal 

